Transmission gear



May 22, 1928. 1,670,403

- J. J. DAVIDSON I TRANSMISSION GEAR Filed May 1-7, 1925 5 Sheets-Sheetl fyzzormyp- 'J. J. DAVIDSON TRANSMISSION GEAR Filed May 17, 1925 M lliv I %\w May 22, 1928.

May 22, 1928. A

. J. J. DAVIDSON- TRANSMISSION GEAR Filed May 17 1925 3 Sheets-Sheet 5PATENT OFFICE.

JOSEPH J. DAVIDSON, 0] DULUTH, MINNESOTA.

rmsmrssron GEAR.

Application filed Kay 17, 1926. Serial No. 108,488.

My invention relates to improvements in transmission gears for changinthe speed ratio between the engine and a riven member and isparticularly applicable for use in connection with heavy machinery suchas rail cars, locomotives, caterpillar tractors and the like wherespeeds are comparativel low and the weights moved are great. t has forone object to provide a transmission wherein the lower speed is alwaysin mesh until the instant that ,the higher speed goes into operation sothat there is no pause between gear shifts and so that the drive iscontinuous throughout the entire length of speed change. Another objectis to provide the transmission wherein the throwing into gear of ahigher speed automatically disengages the gear of the lower speed. Otherobjects will appear from time to time throughout the specification andclaims.

My invention is illustrated more or less diagrammatically in theaccompanying drawings, wherein-- Figure 1 is a plan view of the transmission;

Figure 2 is a section along the line 22 of Figure 1;

Figure 3 is a section along the line 3-3 of Figure 2;

Figure 4 is a section along the line H of Figure 2;

Figure 5 is a section on an enlarged scale along the line 5-5 of Figure2;

Figure 6 is a similar section showing parts in different position;

Figure is a section along the line 7-7 of Figure 6;

Figure 8 is a plan view of the clutch Figure 9 is a plan view of aclutch ring;

Figure 10 is a section along the line 10-10 of Figure 9.

Like parts are indicated by like characters throughout the specificationand draw- 111 s.

3A are the longitudinal and A A are the cross members of thetransmission frame. A is a tight fulcrum member forming a part of theframe. A A are bearings mounted on the frame and carrying the jack shaftA which has at either end the drive sprockets A. Rotatably mounted onthe shaft A are the miter gears A, A for forward and reverse. A is aclutch splined on the shaft A adapted to be moved selectively into orout of engagement with one or the other of the gears A A by means of theforked control lever A pivoted on the member A The clutch A is slottedat A to engage the forked lever A and is provided at either side withteeth A 1 adapted to mesh selectively with teeth A in the gear A andteeth A in the gear A, the distance between the teeth being such thatthe clutch may be in neutral as indicated in Figure 4 or may be moved tothe right or left through reverse or forward as the case may be.

B is a drive shaft adapted to be driven by any suitable source of powersuch as an engine. B is a flexible coupling connecting the drive shaftwith the transmission shaft B which shaft is mounted for rotation inbearings B on the cross members A In line with the transmission shaft Bis a direct drive shaft B mounted in bearings B on two of the crossmembers At. This shaft is out of contact with the shaft B and ends in amiter inion B in mesh at all times with the miter gears A and A. B is anidler shaft mounted for rotation in bearings B on the lower parts of thecross members A B is a gear keyed on the direct drive shaft B in meshwith a pinion B keyed on the idler shaft B. The gear B comprises anouter ring and a central hub portion 13 with a ratchet mechanism B whichwill be later described in connection with other parts of the apparatus.This ratchet mechanism is interposed between them so that when the gearB is driven by the gear B the shaft B is rotated but when the shaft B isrotated by means other than the gear B", the gear B stands still whilethe hub B rotates, and thus the shaft B may face C and theelectromagnetic clutch in the usual manner takes the drive givin adirect drive between the shafts B and B". \Vhen the magnetic coil is notexcited the spring disc C draws the ring C aWa-y from the driving face Cso that the two members may rotate independently.

Rigidly mounted on the shaft B adjacent its outer end is a similarelectromagnetic clutch drum D havin coils D excited by electric currentsupplied through the slip rings D and brushes D. This clutch has adriving face D in opposition to a. driven ring D on a springspider Dmounted on the hub D rotatable on the shaft B- When the members D and Dare drawn together, the shaft B drives the hub D which hub carries apinion D in mesh with a ring gear D. This rin gear D? by means of theratchet mechanism indicated in part at D drives the hub D keyed to theshaft B and this drives the inion B B", hub B and the shaft B. ince thepinion D is very small this gives the first or last speed or drive.

Referring now to Figures 5 to 10 inclusive, it will be noted that thering gear D is free to rotate on the cage E. This cage is made up of aflange E a segmental drum E and a removable flange E and is mounted totravel on the hub D. The two drum segments E are discontinuous and arein sliding engagement with a plurality of ratchet teeth E on the insideof the ring 'gear D". E E are dogs pivoted in the hub D and adapted eachto work in the space between the abutting ends of the drum segments B,being forced outwardly into engagement with the ratchet teeth by thespring E the hub being cut away so that the dogs may be withdrawn insidethe outer periphery of the drum segments E that is, so that they may bemoved from the position in Figure 5 where they engage to the positionshown in Figure 6 where they do not. This withdrawal of the dogs may becaused by the rollers E on the inner sides of the flanges E E theserollers engaging cam surfaces E on the dogs E". In Figure 5, the partsare shown in the. driving position, If, 7 however, by means subsequentlydiscussed the speed of rotation of. the shaft B is increasedsufficiently, the dogs will run away from the ratchet teeth from theposition shown in Figure 5 to the posltion shown in F igure,6 until theycatch up with the rollers E. These rollers will then ride up on the camsurfaces E compress the springs E and force the dogs into the positionshown in Figure 6 thus breaking the drive. If at some later time thespeed of the shaft B drops a reverse motion will take place, the dogswill be released and. will engage the ratchet teeth.

Assuming that the parts are in the posi tion shown in Figure 5, for thelow speed gear and the pinion D is driving if we now excite theelectro-magnetic clutch F, the shaft B will then drive the pinion F Thispinion being larger than the pinion D will cause the shaft B to travelat a faster rate of speed. The shaft B will then cause the hub D to runaway from the ring gear D and the parts will assume the position shownin Figure 6 and drive at a relatively higher speed is permitted from theshaft B through clutch F, pinion F ring gear F to the shaft B. As soonas this drive is established the current can be turned off, the clutch Dand the member D D hub D pinion D" and ring gear D will remain at restwhile the hub D continues to rotate. For the next speed change themagnetic clutch F 3 may be excited, then the drive is through the pinionF ring gear F and hub F to the shaft B. The next speed chan e will becaused by exciting the clutch I" when the drive is through the pinion 1?gear F 9 to the shaft B. The next change to direct dri e will be causedb exciting the clutch C. The speeds can e dropped back to any intermediate speed or to a lower speed by merely reversing the process. Ineach case during the time that the dogs are in engagement for the lowerspeed drive, the shaft merely runs away at such a rate of speed that thedogs do not work and they are left behind one after another. The load isalways picked up from a lower speed and accelerated to a higher speed ordropped back from a higher speed to a lower speed without everdiscontinuing the low speed drive until the high speed has taken more orwithout ever allowing the low s eed drive to take off until the highspee has let go. The drive is thus always continuous. Any number ofspeed combinations can be had merely by increasing the number ofclutches and changing the relation between the drive for each successiveclutch. The speed control is electrical without any mechanical controlwhatever because all that is necessary is to excite successive clutchesand the means for doing this, that is the electric controller todistribute the current to successive electromagnetic clutches is nothere shown as they form no part of my present invention.

It will be evident that while I have shown in my drawings an operativedevice, still many chan es might be made in the size, shape, num er andarrangement of parts without departing materially from the spirit of myinvention and I wish therefore that my showing be taken as in a sensediagrammatic.

I claim:

1. In a transmission gear, a drive shaft and a driven shaft arranged inline one with the other, an electromagnetic clutch interposed betweenthem, a jack shaft extending alongside of both of them, a gearconnection between one end of the jack shaft and the driven shaft, anover-running clutch associated with the gear a lurality of gear trainsinterposed between t e driving shaft and the jack shaft, se arateelectromagnetic clutches associated wit each gear train, and

an over-running clutch associated with each gear train.

2. In a transmission gear, a driving and a driven shaft arranged in linea clutch in-. terposed between them, a jack shaft and a gear trainincluding an over-running clutch interposed between the jack shaft andthe driven shaft, a pluralityof gear trains of different ratiointerposed between the driv-v ing and jack shafts, including over-runninclutches and control clutches one of eac with each gear train.

3. In a transmission gear a drivin a driven shaft, a jack shaft associaand with them, a control clutch interposed between the driving and thedriven shafts, a gear train including an over-running clutch interposedbetween the driven and the jack shafts, a lurality of gear trainsinterposed between t e drivlng and the jack shafts for different ratios,there being associated with some of the gear trains over-running andcontrol clutches.

Signed at Duluth, county of Saint Louis and State of Minnesota, this29th day o April, 1926.

- JOSEPH navinsou.

